2009-10 Sub-ice Current Velocities Recorded with an Acoustic Doppler Current Profiler

Abstract:

On 7 January 2010, a SonTek Argonaut-XR 1.5 MHz Acoustic Doppler Current Profiler (ADCP) was fixed at the bottom of the lake ice in the Lake Hoare Limno Hole inside the Polar Haven, looking downward through the water column. Every 10 seconds, the ADCP measured horizontal and vertical current velocities in ten, 30-cm-thick cells between 0.5 and 3.5 m below the lake ice. Over 32.5 hours, horizontal currents in the shallowest cell (0.5 to 0.8 m below lake ice) had a mean speed of 23.8 cm/sec. This speed was independently validated by lowering a SonTek handheld Acoustic Doppler Velocity (ADV) meter into the ice hole. Horizontal speeds oscillated between 10.1 and 37.5 cm/sec over the course of the ADCP dataset. Fast Fourier Transforms of x-direction velocity data from the shallowest cell identified oscillation periods of 11, 3.7, and 2.5 minutes consistent with the theoretical first-mode longitudinal surface seiche in Lake Hoare. Current direction oscillated between N 78 degrees E and N 289 degrees E along the east-west longitudinal axis of the lake, consistent with the behavior of a seiche.

Dataset ID:

Associated Personnel:

Data sources:

LIMNO_ANCILLARY_ADCP

Methods:

Location: Limno Sample Hole, Lake Hoare, Taylor Dry Valley
GPS: S77°37.660’, E162°54.572’
7 January 2010, 10:50 p.m. to 9 January 2010, 7:24 a.m. (New Zealand Time).
Duration: 32.5 hours
Time correction: Add 18 hours to the raw data times to convert to the New Zealand Time Zone used in the McMurdo Dry Valleys and to synchronize sample times with other datasets provided on MCM-LTER web site.

7 - 9 January 2010 Methods and Settings

ADCP fixed to a metal pole to minimize motion
ADCP inverted and arrow aligned with North such that:
1. +x is West, -x is East
2. +y is North, -y is South
3. +z is Down, -z is up
True current direction (degrees from N) = 360 – observed direction
ADCP lowered to the bottom of the limno ice hole top of ADCP near the ice-water interface.
ADCP diagnostics test performed
Tarp placed over sample hole during deployment
1. Averaging Interval: 10 seconds
2. Sampling Interval: 10 seconds
3. Quality of data: Good.
4. ADCP resolution = plus/minus 0.1 cm/sec.
5. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided
6. Total ice thickness: 3.3 m
7. Distance from piezometric surface to base of ice: 2.8 m
8. Date ice thickness measured: 7 January 2010
9. "Automatic Boundary Adjustment" used
10. Coordinant system "XYZ" Averaging Interval: 10 seconds
11. Sampling Interval: 10 seconds
12. Quality of data: Good.
13. ADCP resolution = plus/minus 0.1 cm/sec.
14. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided
15. Total ice thickness: 3.3 m
16. Distance from piezometric surface to base of ice: 2.8 m
17. Date ice thickness measured: 7 January 2010
18. "Automatic Boundary Adjustment" used
19. Coordinant system "XYZ"
20. Averaging Interval: 10 seconds
21. Sampling Interval: 10 seconds
22. Quality of data: Good.
23. ADCP resolution = plus/minus 0.1 cm/sec.
24. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
25. Total ice thickness: 3.3 m
26. Distance from piezometric surface to base of ice: 2.8 m
27. Date ice thickness measured: 7 January 2010
28. "Automatic Boundary Adjustment" used
29. Coordinant system "XYZ"
30. "Profile Mode" used
31. : Averaging Interval: 10 seconds
32. Sampling Interval: 10 seconds
33. Quality of data: Good.
34. ADCP resolution = plus/minus 0.1 cm/sec.
35. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
36. Total ice thickness: 3.3 m
37. Distance from piezometric surface to base of ice: 2.8 m
38. Date ice thickness measured: 7 January 2010
39. "Automatic Boundary Adjustment" used
40. Coordinant system "XYZ"
41. "Profile Mode" used
42. : Averaging Interval: 10 seconds
43. Sampling Interval: 10 seconds
44. Quality of data: Good.
45. ADCP resolution = plus/minus 0.1 cm/sec.
46. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
47. Total ice thickness: 3.3 m
48. Distance from piezometric surface to base of ice: 2.8 m
49. Date ice thickness measured: 7 January 2010
50. "Automatic Boundary Adjustment" used
51. Coordinant system "XYZ"
52. "Profile Mode" used
53. Cell thickness: 0.3 m; Averaging Interval: 10 seconds
54. Sampling Interval: 10 seconds
55. Quality of data: Good.
56. ADCP resolution = plus/minus 0.1 cm/sec.
57. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
58. Total ice thickness: 3.3 m
59. Distance from piezometric surface to base of ice: 2.8 m
60. Date ice thickness measured: 7 January 2010
61. "Automatic Boundary Adjustment" used
62. Coordinant system "XYZ"
63. "Profile Mode" used
64. Cell thickness: 0.3 m
65. Averaging Interval: 10 seconds
66. Sampling Interval: 10 seconds
67. Quality of data: Good.
68. ADCP resolution = plus/minus 0.1 cm/sec.
69. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
70. Total ice thickness: 3.3 m
71. Distance from piezometric surface to base of ice: 2.8 m
72. Date ice thickness measured: 7 January 2010
73. "Automatic Boundary Adjustment" used
74. Coordinant system "XYZ"
75. "Profile Mode" used
76. Cell thickness: 0.3 m
77. : Averaging Interval: 10 seconds
78. Sampling Interval: 10 seconds
79. Quality of data: Good.
80. ADCP resolution = plus/minus 0.1 cm/sec.
81. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
82. Total ice thickness: 3.3 m
83. Distance from piezometric surface to base of ice: 2.8 m
84. Date ice thickness measured: 7 January 2010
85. "Automatic Boundary Adjustment" used
86. Coordinant system "XYZ"
87. "Profile Mode" used
88. Cell thickness: 0.3 m
89. Number of cells: 10; Averaging Interval: 10 seconds
90. Sampling Interval: 10 seconds
91. Quality of data: Good.
92. ADCP resolution = plus/minus 0.1 cm/sec.
93. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
94. Total ice thickness: 3.3 m
95. Distance from piezometric surface to base of ice: 2.8 m
96. Date ice thickness measured: 7 January 2010
97. "Automatic Boundary Adjustment" used
98. Coordinant system "XYZ"
99. "Profile Mode" used
100. Cell thickness: 0.3 m
101. Number of cells: 10; Averaging Interval: 10 seconds
102. Sampling Interval: 10 seconds
103. Quality of data: Good.
104. ADCP resolution = plus/minus 0.1 cm/sec.
105. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
106. Total ice thickness: 3.3 m
107. Distance from piezometric surface to base of ice: 2.8 m
108. Date ice thickness measured: 7 January 2010
109. "Automatic Boundary Adjustment" used
110. Coordinant system "XYZ"
111. "Profile Mode" used
112. Cell thickness: 0.3 m
113. Number of cells: 10; Averaging Interval: 10 seconds
114. Sampling Interval: 10 seconds
115. Quality of data: Good.
116. ADCP resolution = plus/minus 0.1 cm/sec.
117. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
118. Total ice thickness: 3.3 m
119. Distance from piezometric surface to base of ice: 2.8 m
120. Date ice thickness measured: 7 January 2010
121. "Automatic Boundary Adjustment" used
122. Coordinant system "XYZ"
123. "Profile Mode" used
124. Cell thickness: 0.3 m
125. Number of cells: 10; Averaging Interval: 10 seconds
126. Sampling Interval: 10 seconds
127. Quality of data: Good.
128. ADCP resolution = plus/minus 0.1 cm/sec.
129. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
130. Total ice thickness: 3.3 m
131. Distance from piezometric surface to base of ice: 2.8 m
132. Date ice thickness measured: 7 January 2010
133. "Automatic Boundary Adjustment" used
134. Coordinant system "XYZ"
135. "Profile Mode" used
136. Cell thickness: 0.3 m
137. Number of cells: 10
138. Approximate depth range of ADCP cells: Averaging Interval: 10 seconds
139. Sampling Interval: 10 seconds
140. Quality of data: Good.
141. ADCP resolution = plus/minus 0.1 cm/sec.
142. ADCP accuracy = plus/minus 0.5 cm/sec. Files for standard deviations and signal-to-noise ratios provided.
143. Total ice thickness: 3.3 m
144. Distance from piezometric surface to base of ice: 2.8 m
145. Date ice thickness measured: 7 January 2010
146. "Automatic Boundary Adjustment" used
147. Coordinant system "XYZ"
148. "Profile Mode" used
149. Cell thickness: 0.3 m
150. Number of cells: 10
151. Approximate depth range of ADCP cells:
  1. Rel. to bottom of the lake : Rel. to piezometric surface
  2. Cell 1: 0.5 to 0.8 3.6 to 3.9
  3. Cell 2: 0.8 to 1.1 3.9 to 4.2
  4. Cell 3: 1.1 to 1.4 4.2 to 4.5
  5. Cell 4: 1.4 to 1.7 4.5 to 4.8
  6. Cell 5: 1.7 to 2.0 4.8 to 5.1
  7. Cell 6: 2.0 to 2.3 5.1 to 5.4
  8. Cell 7: 2.3 to 2.6 5.4 to 5.7
  9. Cell 8: 2.6 to 2.9 5.7 to 6.0
  10. Cell 9: 2.9 to 3.2 6.0 to 6.3
  11. Cell 10: 3.2 to 3.5 6.3 to 6.6

Supporting file links (Standard Deviations, etc)

"ADCP set up 7- 9 January 2010 This text file lists more details about how data were recorded. Link here
"ADCP signal to noise ratio 26-30 Dec 2012" This file provides diagnostic data on the instrument which someone might find useful. Link here
"ADCP standard deviation 26-30 Dec 2012" This text file provides information on sampling error.Link Here

Additional information:

Data contained in these files has been subjected to quality control standards imposed by the investigator. The user of this data should be aware that, while efforts have been taken to ensure that these data are of the highest quality, there is no guarantee of perfection for the data contained herein and the possibility of errors exists. If you encounter questionable data, please contact the MCM LTER data manager corrected or qualified. Thus, these data may be modified and future data will be appended.